“In the table for column 1 the letter G occurs 9 times,” he says with an air of a man having found something that is perfectly plain. “Let us consider it tentatively as E.
“Then, if the cipher alphabet runs regularly and in the direction of the regular alphabet, C (7 times) is equal to A, and the cipher alphabet bears a close resemblance to the regular frequency table. Note that TUV (equal to RST) occurring respectively 7, 7, and 5 times and the non-occurrence of B, L, M, R, S, Z (equal to Z, J, K, P, Q, and X, respectively).
“In the next table L occurs 19 times, and taking it for E with the alphabet running the same way, A is equal to H. The first word of our message, CT, thus becomes AM when deciphered with these two alphabets, and the first two letters of the key are CH.
“Similarly in the third table we may take either F or O for E, but a casual examination shows that the former is correct and A is equal to B.
“In the fourth table I is clearly E and A is equal to E.
“The fifth table shows that T is equal to 14 and J is equal to 9. If we take J as equal to E then T is equal to O, and in view of the many Es already accounted for in the other columns this may be all right. It checks as correct if we apply the last three alphabets to the second word of our message, OSB, which deciphers NOW. Using these alphabets to decipher the whole message we find it to read:
“‘M. B. Am now safe on board a barge moored below Tower Bridge, where no one will think of looking for me. Have good friends but little money owing to action of police. Trust, little girl, you still believe in my innocence although things seem against me. There are reasons why I should not be questioned. Shall try to embark before the mast in some outward-bound vessel. Crews will not be scrutinized as sharply as passengers. There are those who will let you know my movements. Fear the police may tamper with your correspondence, but later on, when hue and cry have died down, will let you know all.’”
It all seems simple to the man who follows the idea closely, but Captain Hitt proceeds to make further revelations of the art. He adds:
“The key to this message is CHBEF, which is not intelligible as a word, but if put into figures, indicating that the 2d, 7th, 1st, 4th, and 5th letter beyond the corresponding letter of the message has been used as a key it becomes 27145, and we connect it with the personal which appeared in the same paper the day before reading:
“‘M. B. Will deposit £27 14s. 5d. tomorrow.’”